how to check for record NOT existing in another table by user ID number?

If users in a database are identified by ID number, lets say there are two tables:

tbl1.userid
tbl2.userid

tbl1 is the main table -- every user in the system has a single record (userid is unique)

tbl2 contains info about the user saved at various times -- every user could have many records or they could have zero records (many records in this table with the same userid)

How could I figure out which tbl1.userid is MISSING a record in tbl2? In other words, I want to select all userid's where nothing has ever been entered in tbl2 for the user.

I am currently doing this with ASP scripting but it is inefficient that way, because I have to loop through thousands of userid's and then do a 2nd query to check against tbl2. I'm guessing there is a better way.

Thank you!